TRV has 30mm fixing ring body 15mm fiitings. The Chrome finish TRV valve and Head Unit is a stylish and efficient central heating radiator accessory. With a timerless control, hydronic power source, and compatibility with boiler heating systems, this unit offers convenient and effective heating management. The vertical radiator orientationmake it a practical choice for any home. Additionally, the included thermostat ensures precise temperature control for enhanced comfort and energy efficiency.